to milwaukee, indianapolis to chicago, it's been a week of heat, humidity and heavy rain. >> you can call this the summer of the heat wave. outside of southern california this could go down as the top five hottest summer for many cities. >> reporter: in ames, iowa, the entire city is without clean running water after heavy flooding. >> thank you. >> yep. >> reporter: the weather channel's janelle cline is there. >> much of iowa is damaged after rains. massive flooding closed interstates, swept cars off roads, even killed a 16-year-old girl. >> reporter: while in chicago, another problem -- a mosquito population explosion. and the dragonflies that eat them. >> they're all over. just like a swarm of what you would imagine locusts. >> reporter: back here in d.c., forecasters say this is likely to go down as one of the hottest summers on record, following record snowfall over the winter. climatologists say it is linked to global warming. the hotter it gets, the wetter it gets, the more violent the storms are and the more moisture we have. ann, back to you. >> all right. tom costello, thanks.